Rear mount for fixed machine guns



Sept. 4, 1945. P, 066 v 2,383,985

REAR MOUNT FOR FIXED MACHINE GUNS .Filed Feb. 4, 1944 INVENTOR PGE A? 066 v a 'L ATTORNEYS 1 moves about during firing, which destroys Patented Sept. 4, 1945 Q} REAR MoUNTFonrIXEDMAcnrNEGUNs,

George i s; Springfield, Ohio" np ucationreb lsiy 4, 1944, Serial No. 521,100

20min (c1.ss-sms 'ff, v

' 9 (Granted under the act of March 3.18%, as v V w w 7 amended April 30, 1928 3'70 0. G. 757) invention described herein maybe mar factured and used by or for the Government for H governmental purposes, without the payment to me of any royalty thereon.

This invention relates to the. rear mounts tor fixed machine guns, such as,are commqn1 m stalled on aircraft, especially interceptor; or fight-,

er airplanes. 1 V

Objects of the invention are to provide a rear mount which is easily; installed, which permits;

quick attachment and detachment of the machine gun, and which allowsfor any misalignment that may exist between the airplane parts which support the front and rear mounts of the machine, gun, sothat no severe stresses are imposed ;onthe rear mount, and thegun may be firedin mount or the".

definitely without failure of said connections therewith.

.The present type A-4 quick detachable rear gun mount for the Browning caliber .50 machine gun comprises, in general, a screw nthreade'd :post-S; which is attached to the, airplane part that pro-a vides the support, a holder attached by a bolt. totwo perforated ears depending from the res; ceiver assembly of the gun, and aball locking.

joint comprising three steel balls which. look the.

holder to the post-in one position, andi releasei the holder in another position, the releasing being efiected by turning a knurled collar through 90.

against'a torsional spring. A general idea of this construction may beobtained by referring to the Hofstetter Patent vNo. 1,939,699, dated December 19,1933, which, however, differs inthat the'collarcontrolling-the locking balls" is slidable instead:

'ofoscillatable. 1 w The gravest objection to thetype- A-4 mount (also to the Hofstetter construction) is that no provision is madefor taking care of misalignment In cases between the frontand rear mounts. where the front and rear mounts'are bolted to a single casting, misalignment is less likely to- Occur;- but when the machine guns are mounted,

for example, in thewings of airplanese'specially pursuit or fighter planes-the very light metal to which the machine gun mounts are secured almost certain to become slightly twisted or'bent under the terrific stresses encountered in military maneuvers and in battle; so that the armorer is the reaction on the mount from recoil forces .due

to the 'firing' of the The'result is that the rear mount either b'reaks'loose entirely or else' -tl'1'e 55 while the operations continue), and by adding clamps and safety wires to the rear mount;v to' prevent disconnection thereof, but the latter ex pedient has proved to be highly unsatisfactory,-;- as the mounts have continued to fail. The accompanying drawing shows the embodipreferred by me. In';

ment of the invention now said drawing.

Fig. 1 is aside elevation showing-inz phantom part of a machine gun supported'on a standard front mount and on a rear mount made in ac-. portions of bothcordance with the invention, mounts being omitted;

Fig. 2 is an elevation, in full size, showing the entire rear mount;

Fig. 3 is an elevation of the same omitting-the lower portion of the post, the mount being viewed from the right side of Fig. 2;

Fig. 3;

Fig. 5 is a detail elevation of the locking pin per se and cooperates with the l the pin in the desired position.

Referring particularlyto the drawing, themaj chine gun G is shown inFig. 1 as supported by; a type A3 gun mount H, at the forward end of] the receiver assembly, said gun mount Comprising. N a post l2 adapted tov be secured .to theiairplane or other support, a U-shaped adapteriii secured '1 by bolt Hi to the receiver assembly, and a mel ing; collar 15 which is turned about 90 againstthe f resistance of a, torsional spring (not shown) to release three locking balls (not shown) which look the post and adapter together. A more detailed description is omitted as the type A -3 gun mount forms nopart of the present invention.

It is important to understand that gun mount ll is designed to absorb the entire recoil of the gun and provides a support permitting elevation:

or azimuthadjustment of the gun about the axis of bolt [4 or about the axis of post l2 respectively,';- while the rear gun mount I6 (which istheinvention herein described) is essentially a steady rest-- and may be manipulatedto providebotheleva- Fig. 4 is a longitudinal-section on line 4 1 of tion and azimuth adjustment of the gun, and in addition, may compensate for any misalignment of the supports, as will be made clear.

Referring to Figs. 2, 3 and 4, the rear mount I 6 comprises a screw threaded post adapted to be secured to an airplane or other support by means of nuts 2I,.22 and washers 23, 24. The upper end -i of" the postlis free of screw threads and has two flattened faces on opposite sides. At its upper extremity, the post has a transverse slot 26 opening from the top, and a transverse bore 21 open to the slot and extendin'g between the flattened faces 25. The bore 21 has adiameter larger than the width of the slot. "Thus, the upper end of the post; is bifurcated: and mayreceive a locking pin, as will be explained. l,

A holder 3|] is adapted to be secured to the gun G by means of a bolt 3| whichpasses throughtwo spaced perforated lugs 32 (only-'one ofswhich is shown) depending from the receiver assembly.

Bolt 3| preferably hasai"longitudinal sl0t" 33 to* receive a key '3 4'' fixed to the-interior of a *holl ow sleeve 3 5 whichhas*s'crew threads on us -exterior" to-engage a-tappedbore 36 iii-the holder-: Thusrotation of'--' bolt '3'lwill cause' 'the sleeve to" move ino'ne direction or theother thrcugh the holder, but irrespectiveof the'-- position of" the" sleeve in the holder, the b'olt is sl-idable relative= toth'e sleeve-to permit-thebolt -to' be drawnup tight when attaching the gun to the giimmountt also to permit withdrawal of the bolt by hand; when disassemblingz'the'gun mount. However-ti the spaced lugs 32 snugly fit in the spaees between the. head of the.v bolt'wandi one-end'to-fri screwthread'ed sleeve-35; .andawasher: 39iand thefother" end of sleeve 35, so that bolt 3! cannotzslicleiat all). when. the parts are fullyassembled: .zThe sleve. is.c1amped. relative: to: the: holderrby; means 1 of a set screw 3J threaded intoia bossn3-7winithe holder, the setscrew preferably having-a -fiaten-d (Fig. 4) and being self lockingnand shake-proof Anut 38,.lock Washer 39 and-loch nutl ifl complete the assembly for attaching the:=gun.t0-'the mount. I

Depending from'the holder-are-twol-spaced parallel lugs 4| having aligned circular-bores 42 to receivelallocking pin-43l Theloeking pin is of generally circular cross section but has flattened areas- 44 on diametrically, opposite-sides, and these areas lie between the lugs 41, so that round-- portions of I the. locking pin -may turnwithinflthe circular bores 42. Thelocking. pin isuthus .rotatable and slidable on. the. holder. 7 A'- flat n'iet'al thumb-piece. 45.is.secured. by cross pin 461 within a slot 4Tcut into one end 'of'the. lockingpin and has projections 48"adapted'to" be" receivedin notches cut in the outer vertioalface 'offori'eof the lugs '4'II These notches are. arrangedias' twof spacecl'aligned'notclies 49"011 opposite sidesbf" bore 42; and two alignedspacednotches51]at rightangles -to notches! "andlikewise'locate'd'on" oppOsitesides of bor'e42; A'zsheetmetal' spring 5 I; shown" separately in Fig. 6;; has a bore" '52 1 adaptingit to fit over-the locking pi-n,- and a washer" 53 holds-thespringin position; being turn held on the-locking pin by-- a cotter pi-n 54- or; if preferred;- by-a cross pin- (notSHOWm secHred by a press fit in cross -bore 55i I'he' spring 5l tends 4 to pull thelocking 'pin to th'e left as the parts are. viewed a in Figs 2- 1 and; and: hen holds the projections seated in'theznotchesfla on 50",: .as the case .may. be; Th zilockmgipin is! locked. against turning when 1 projections- 48 areseatedin said notches I As .Figs.' 2'- and 4 show; ,thewlugs fl are spacedapart sufiiciently to slip freely over the flattened upper end of the post. If the locking pin is turned so that its flattened areas 44 are vertical, the locking pin will pass laterally through the slot 26 in the top of the post before the locking pin seats in the bore 21. By turning the locking pin 90 it willwmove out of the notches 50 and into theinotches lil, wliichbrin'gs tfi'e mund portion of the locking pin under the slot 26, thereby rigidly locking the holder to the post. Another tiirn of 90 will bringthe flattened areas around until 'tl'ieyare be'neath the walls of slot 26, whereupon the gun assembly may be lifted and the locking pin will slide out through said slot to. release tlie parts; Obviously the described construction provides a manually releasable, quickdetacl'iablelock for the holder and post.

v One ofthe=- features of the invention is that the locking and: unlocking are dependable. An-

' that post 2 0 lan's= slightly rearward" relative-w other is the ease of assembly and disassembly which willbe obvious-witlioutfurther description. After exhaustive fieldte'sts bythyA'r'rny air forces; the" device"o'f the present invention has been adopted as standard"'e'quipment -andf is known as th'ety*pe=A -5gi1rrm0unt The outstaiiclil' lg advantage of myguii mdunt is" the-fact that'any-n*iisaligntiient wliic l'i Ih'aifli encountered is taken care of without stre'ssii1g or' straining the mount-or themairts to "Whielidt is'attache'dL- If the rea'r'" mount is sosiipported' ensated' b yrearward sliding and pivoting of the? holder. The gun is; free to: rfock on' tlie 'po'st through asn iau angle becaus eane -toppf'the is spaced from the bottom of th holder betw'e'en the-lugs) nurthermorez the gun maynsatijustedin azimuth 'at any tim by merely iocsen ingthe se t screw 31 an d' t111fi-1h means of the 'bolt .3 lgxthen tightening the: sen screw to hold: thew-adjustment; Elevation and depression: adjustment-of l the gunisi'ori courseefiected by the screw threa'ded post 20; I-ho small 1- spaces ishown in Fig; 2:as lyingtzbetwe'en tlie inner. faces-50f lugs. Al ontherho'lder, and thafiait tenedfifaces 2 51 at the'top ofi the' -post, la'resof con sid'erable-importance when assemblingl the gun 'on i the forward an'd rear gun I mountsgub'ecause ztliesec spaces ipermit takingcare-t o'fi slight :difierencesiin' the airp1ane:'structurei which suppbrtswthe gimfj mounts; also-take care'i of si ig ht' vari'atio-nsi-iii-ithf position of th'e frontgun mount reIati-ve to; the:

rear gun mount, and also take care?of: nt-ami facturingtolerancesi in: the? itself.- -In= the .50 :cal; Brownin'g ma'chi-ne 'gun qthe manufactur-- ingto1eranceis -i .020 in.' in the: distance between i the: centers of: the =frontand rear' mou ntsw The described gunmount may 'however be used -with any caliberiof machine guniv p i While for convenience the 'term-s= vertical-, !v elevation and: azimuth have been: used; it; will be. understood' that machines-guns are: irequently: mounted at an angle -t0 the verticaland I a normal elevational 1 mover-merit may have a component of: azimuth while a normal azimuth adjustment may-have a pomponentof elevation.-- Various combinations of theseveral adjustments are possible to make the E rear mount mere-1 p a: steady rest for the-gun, -with practicall-y5 .no, stresses tendings to loosenthe connections. The; low I stresses to which the mountds subjected are: easily taken -care of by'the rugged =-de sig-n;--of the:

the' sleeve 35 by What I claim is:

1. A rear gun mount for machine guns comprising, in combination, a post adapted to be secured in an upright position on an airplane or other support, said post having its upper end bifurcated, with a transverse slot open to the upper end and a transverse bore, of larger diameter than the width of the slot, located below and open to the slot; means for adjustably securing the post upon said support; a holder; means for connecting the holder with the gun; a locking pin on the holder adapted to pass laterally through the slot when turned to a certain angular position; said locking pin locking in the bore when turned through a predetermined angle from the position it had when it was passed through the slot but being sli-dable in the bore when so locked; and manually releasable meansto secure the locking pin in various angular positions; the locking pin permanently securing the post and holder in properly assembled relationship, when locked in said transverse bore; said holder having two depending lugs with aligned bores for receiving said locking pin, said lugs being spaced apart a distance greater than the width of the top of the post 'so that the holder may have limited rectilinear movement on the post as determined by the sliding fit of the locking pin in said transverse bore and as limited by contact of the insaid locking pin axis being below and substantially parallel to the longitudinal axis of the gun when connected to said holder.

2. A gun mount comprising, in combination, supporting means adapted for direct and rigid attachment to an airplane or other support;

means to adjust the supporting means to effect vertical adjustment of the gun; clamping means mounted on the supporting means for securing the gun to the supporting means; said clamping means being rockable about a horizontal axis which is parallel to the vertical plane coinciding with the longitudinal axis of the gun; means forming part of the gun clamping means and constructed and arranged so that the latter is adjustable in the straight line laterally relative to the gun, to move the gun in azimuth; and means interposed between the gun clamping means and the supporting means and constructed and arranged to permit slight straight line movement of the gun, when clamped, relative to the supporting means and in said vertical plane.

GEORGE P. OGG. 

